<?php
global $wpdb;
delete_option("hfr_db_version");

require_once(ABSPATH . '/wp-admin/includes/upgrade.php');

$sql = "DROP TABLE IF EXISTS `".$wpdb->prefix."hfr_url_craw`";
$wpdb->query($sql);

$sql = "DROP TABLE IF EXISTS `".$wpdb->prefix."hfr_payment`";
$wpdb->query($sql);